Grover Norquist has never held elected office. He's not a political appointee or a congressional staffer, and few voters know his name. Yet this anti-tax lobbyist wields immense power over the Republican Party, enforcing a hard-line position that compels the GOP to protect tax breaks for the rich and billions in federal subsidies for America's wealthiest corporations. "It all comes from a single guy," says Alan Simpson, the former Republican senator. So how does Norquist do it?

Norquist's influence over the GOP began in 1985, when Ronald Reagan tapped the little-known staffer at the Chamber of Commerce to head up Americans for Tax Reform, a pressure group organized to push a comprehensive tax package through Congress. With backing from the Chamber, Norquist – a Harvard MBA and former head of the College Republicans – challenged GOP candidates to take a two-part pledge: that they would never raise taxes, and that they would only close tax loopholes if the additional revenue was used to pay for further tax cuts. Before long, he had 102 congressmen and 16 senators signed up.

Over the past 25 years, Norquist has received funding from many of America's wealthiest corporations, including Philip Morris, Pfizer and Micro­soft. To build a farm team of anti-tax conservatives, Norquist shrewdly took the pledge to state legislatures across the country, pressuring up-and- coming Republicans to make it a core issue before they're called up to the big leagues. "We're branding the whole party that way," Norquist says. "The people who are going to be running for Congress in 10 or 20 years are coming out of state legislatures with a history with the pledge."

Norquist also built the anti-tax pledge into the DNA of the GOP by hosting weekly Wednesday meetings that enable activist groups representing everyone from gun nuts to home-schoolers to mix with top business lobbyists and conservative officials. The meetings, which began shortly after Bill Clinton was elected, turned Norquist into the Republican Party's foremost power broker – and gave him a forum to enforce the no-new-taxes pledge as the centerpiece of the GOP's strategy. "The tax issue," he says, "is the one thing everyone agrees on."

Norquist cemented his influence by forging an early alliance with Karl Rove and setting himself up as a gatekeeper to George W. Bush's inner circle. Then, after Obama was elected, this ultimate Washington insider positioned himself as a leader of the anti-establishment Tea Party, complete with financial support from the billionaire Koch brothers. "These Tea Party people, in effect, take their orders from him," says Bruce Bartlett, an architect of the Reagan tax cuts. "He decides: This is a permissible tax action, or this is not a permissible tax action. And of course, anything that cuts taxes is per se OK."

Today, GOP politicians who have signed Norquist's anti-tax pledge include every top Republican running for president, 13 governors, 1,300 state lawmakers, 40 of the 47 Republicans in the Senate, and 236 of the 242 Republicans in the House. What's more, the GOP's Tea Party foot soldiers are marshaled by House Majority Leader Eric Cantor – a veteran of Norquist's farm team, who first signed the pledge as an ambitious member of the Virginia legislature. Under Cantor's leadership, Norquist's anti-tax pledge was directly responsible for last summer's debt-ceiling standoff that wrecked the nation's credit rating by leading the nation to the brink of default. "Congress was willing to cause severe economic damage to the entire population," marvels Paul O'Neill, Bush's former Treasury secretary, "simply because they were slaves to an idiot's idea of how the world works."